Q. Recently I've run into a couple of incidents where a crystallized white substance has formed on the shower floor and in the drain. In both cases the showers have mud-set floors and are entirely tiled. The water is from a public source. In one case, the

Q. While I was removing the old tile from a concrete shower pan in a slab foundation, a portion of the 1x5-inch raised concrete lip separated from the slab below. It appears that the lip was formed and placed on top of the slab, and there is nothing tying